Battery module with thermal runaway and gas exhaust management system

ABSTRACT

Apparatus, methods and systems are provided for thermal runaway and gas exhaust management for high power batteries. A battery module has a plurality of cell-containing carriers stacked on top of one another to form a cell stack having a front end and a rear end. A duct extends through the cell stack between the front end and the rear end for collecting escaped gases from the battery cells. A self-closing one-way pressure relief valve is located in the duct toward the rear end of the cell stack. The pressure relief valve connects to a piping system for carrying the gases to a remote location where the gases can be safely released and dispersed.

REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Application No. 62/129,116filed on 6 Mar. 2015 and entitled BATTERY MODULE WITH THERMAL RUNAWAYAND GAS EXHAUST MANAGEMENT SYSTEM. For purposes of the United States,this application claims the benefit under 35 U.S.C. § 119 of U.S.Application No. 62/129,116 filed on 3 Mar. 2015 and entitled BATTERYMODULE WITH THERMAL RUNAWAY AND GAS EXHAUST MANAGEMENT SYSTEM which ishereby incorporated herein by reference for all purposes.

TECHNICAL FIELD

The technology described herein relates to high power batteries, andapparatus, methods and systems for managing thermal runaway and gasexhaust from such batteries.

BACKGROUND

Thermal runaway in a battery occurs when rising battery celltemperatures initiate chain reactions that accelerate chemical reactionsin the battery, further contributing to the rapid release of thermalenergy. Thermal runaway may be triggered by insufficient cooling ofbattery cells during operation of the battery. Thermal runaway may alsobe triggered by other events, such as short circuits, mechanical shock,extreme temperature exposure, manufacturing defects, etc. During athermal runaway event, hot gases and other flammable materials mayescape from the battery cells. If not properly managed, the escapedgases may result in a fire or explosion.

High power lithium-ion batteries are often more prone to thermal runawaythan other types of batteries. As such, there is a need for thermalrunaway management systems for high-power lithium-ion batteries. Thereis a general desire for apparatus, systems and methods that assist withmanaging thermal runaway and gas exhaust from a battery cell, moduleand/or system.

SUMMARY

Aspects of the technology provide a thermal runaway and gas exhaustmanagement system for a battery module. The battery module incorporatesa plurality of cell-containing carriers stacked on top of one another toform a cell stack having a front end and a rear end. The thermal runawayand gas exhaust management system includes a duct extending along orthrough the cell stack between the front end and the rear end forcollecting escaped gases from the battery cells. A pressure relief valveis placed in the duct toward the rear end of the cell stack. Thepressure relief valve connects to a piping system for carrying the gasesto a remote location. In certain embodiments, the pressure relief valveis a self-closing, one-way valve. The pressure relief valve may have anoperating pressure of 7 kPa.

A top plate is placed over the cell stack, the top plate having a slotextending between front and rear ends of the cell stack for receivingthe duct. The top plate is sealed to the cell stack by a gasket. Theduct is sealed to the cell stack by a duct gasket. Gaskets arepositioned between adjacent carriers to seal between the carriers.

Other aspects of the technology provide for methods of manufacturing abattery module incorporating a thermal runaway and gas exhaustmanagement system. According to particular embodiments, the methodconsists of forming a cell stack and positioning a top plate over thecell stack, forming in the top plate a slot extending between front andrear ends of the cell stack, placing a duct within the slot, and placinga pressure relief valve in the duct toward the rear end of the cellstack. The pressure relief valve is connected to a piping system forcarrying gases collected in the duct to a remote location. The pressurerelief valve may be a self-closing, one-way valve.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following detailed descriptions.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiments are illustrated in referenced figures of thedrawings. It is intended that the embodiments and figures disclosedherein are to be considered illustrative rather than restrictive.

FIGS. 1, 2, 3, 4 and 4A illustrate a battery module incorporating athermal runaway and gas exhaust management system according to oneembodiment.

FIG. 1 shows the battery module assembled;

FIG. 2 is an exploded view showing more clearly aspects of the thermalrunaway and gas exhaust management system;

FIG. 3 shows various components of the thermal runaway and gas exhaustmanagement system located at the rear of the battery module;

FIG. 4 shows the battery module with the top plate; and FIG. 4A is adetail view through a portion of the slot in the top plate, showing thespaces between cell carriers.

DESCRIPTION

Throughout the following description, specific details are set forth toprovide a more thorough understanding to persons skilled in the art.However, well known elements may not have been shown or described indetail to avoid unnecessarily obscuring the disclosure. Accordingly, thedescription and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

FIG. 1 shows a representative battery module 100 in which a thermalrunaway and gas exhaust management system is incorporated. Batterymodule 100 consists of a plurality of stacked battery cells. The cellsmay be lithium-ion (Li-Ion) pouch cells or the like, or other types offlat battery cells, such as, for example, flat cells enclosed in metalcases. The cells can be stacked on top of one another (arranged parallelto one another) to make up a cell stack 105 for the battery module 100.Each battery cell may be contained in a cell carrier 104. Cell carriers104 may be similar to the cell carriers described in the applicant'sU.S. patent application No. 62/117,686 filed on Feb. 18, 2015 and theapplicant's PCT patent application No. PCT/CA2016/050149 filed on Feb.18, 2016, which are incorporated herein by reference in their entirety.In particular embodiments, the stacking of cell carriers 104 may befacilitated by interlocking features provided in the frame of the cellcarriers 104. For example, each frame may incorporate complementarytongue and groove connections located on opposing sides of the frame forjoining the cell carrier 104 to adjacent cell carriers 104. An O-ring orother gasket (not shown) may be inserted between adjacent cell carriers104 to seal the connections between the cell carriers. The cell stackmay be secured by straps 103, as shown, or by other means such as tiesor rods. Electrically isolated end caps 106, 108 are provided to cap thecell stack 105's front end 110 and rear end 112 respectively. A topplate 114 is placed on top of the cell stack 105. Top plate 114 mayfunction as a cooling plate. In such case top plate 114 may be made ofaluminum, copper or any other suitable material with high thermalconductivity. Apertures 116, 118 are defined in top plate 114 near thecell stack 105's front and rear ends 110, 112, respectively (over themost positive and negative terminals of the cell stack, see FIG. 2) toallow for electrical power connections to outside of the module 100. Thepower connections can be connected to connectors at the cell stack 105'sfront end 112 by means of a power cable, flexible bus bar, or the like.An electrically isolated cap 120 is placed over the top plate 114 andthe electrical connections to protect against electrical exposure.Cooling systems (not shown, apart from top plate 114) may beincorporated to cool the battery cells, their carriers 104 and module100.

As best seen in the exploded view of FIG. 2, thermal runaway and gasexhaust management system 102 includes a gas exhaust or gas extractionduct 123 extending along a length of the cell stack (i.e. between frontend 110 and rear end 112 of the battery module 100's cell stack 105).Duct 123 is received within a slot 125 defined through a center of thetop plate 114, extending along the length of the cell stack 105. Duct123 may be sealed to the top plate 114 by way of a duct gasket 126. Thebattery cell carriers 104 are sealed between each other by way of thesealed tongue and groove connections between adjacent carriers 104 (asdescribed above). Top plate 114 is sealed to the cell stack by means ofa gasket 165. In this manner, the stack of cell carriers 104 iscompletely enclosed and sealed off from the outside environment. Aself-closing, one-way pressure relief valve 128 is placed in the duct123 at the rear end 112 of battery module 100's cell stack 105. Inparticular embodiments, the operating pressure of valve 128 is 7 kPa(0.07 bar or 1 psi). As seen in FIG. 3, nozzle 130 is connected betweenvalve 128 and a piping system 135. Piping system 135 consists of one ormore pipes that lead to a location, remote from the batteryinstallation, where the exhaust gases can be safely released anddispersed.

In some embodiments, the duct 123 connecting the cell carriers 104 inthe cell stack 105 may be created by the space between the cell carriers104 and the top plate 114. It may also be incorporated as agas-conducting passage in the top plate 114 (e.g. the top plate 114 maybe shaped to provide such a passage). In the illustrated embodiment, theduct 123 is a separate duct that is placed over the cell stack 105. Theduct 123 is shown to be a semi-cylindrical (or approximately asemi-cylindrical) duct. In other embodiments, the duct 123 may have adifferent shape (e.g. round, oval or rectangular). The duct 123 is sizedso as to be capable of removing the amount of gases typically generatedduring a thermal runaway event. In particular embodiments, for example,the duct 123 is semi-cylindrical in shape with a radius in the range of2 to 5 cm.

In the event of a thermal runaway where a battery cell is compromisedand flammable gases escape from the cell, the gases will be forced intoand collected in duct 123. The accumulation of gases within a batterypouch cell will typically cause the pouch cell to open at the top.However, the pouch cell may also burst open at other locations on thepouch. The cell carrier 104 may be designed such that there is a gapbetween the battery pouch cell and the wall of the carrier 104 allaround each pouch cell. Since there are seals between the carriers 104the gasses released anywhere from the battery pouch cell will make theirway to the top of the stack 105 and to the duct 123. The gases thatescape from the pouch cell will be forced into the spaces 121 betweenthe cell-containing carriers 104 and between the cell tabs 122 (seeFIGS. 4, 4A), and will move past the cell tabs 122 and into duct 123.Valve 128 will open once enough gas has accumulated in duct 123 toincrease the pressure in the duct to a first threshold level so as totrigger the opening of the valve (i.e. at the operating pressure ofvalve 128). The operating pressure of relief valve 128 may be low toallow any gas generated to be removed from the battery module 100. Inparticular embodiments, values for the operating pressure are in therange of 5 to 15 kPa (0.5 to 1.5 atmosphere), for example. Once valve128 is opened, the gases that have been collected in duct 123 exitthrough the valve 128 into the piping system 135. Thus, duct 123 andone-way gas pressure relief valve 128 help to manage the gas exhaustfrom the battery cells by carrying the escaped gases out of batterymodule 100 and into a piping system 135. The piping system 135 thentakes the gases to a remote location away from the battery installationwhere the gases can be safely released and dispersed. The distance atwhich the exhaust gases are carried before being released may depend onthe application and environment. For example, in a boat, the gases maybe transported a few meters to the smoke stack. On land, the gases maybe transported several 10s of meters to a location remote from anypeople. The thermal runaway and gas exhaust management system 102prevents the gases from being released in or around the battery module100 where they could otherwise cause a fire or explosion. In addition,once the gases have safely exited the battery module 100 and moved intothe piping system 135, the pressure in duct 123 is decreased below asecond threshold level, causing valve 128 to close. In particularembodiments, the valve 128 is spring loaded, and it will open as soon asthe pressure is above the spring holding pressure and close again whenit drops below that pressure (thus in such embodiments the first andsecond threshold levels of pressure are equal or approximately equal).The closing of valve 128 prevents the return flow of oxygen to batterymodule 100 therefore ensuring the thermal runaway process remainsstarved of oxygen. The closing of valve 128 also ensures that thethermal runaway exhaust gases do not re-enter the duct 123 where theycould heat and affect the performance of the battery cells in the cellstack 105. Any components exposed to the hot gases, such as the gasextraction duct 123, pressure relief valve 128 and piping system 135 maybe made of aluminum, steel or stainless steel, or any other suitablematerial that is heat resistant. In particular embodiments, thecomponents are heat resistant up to 400° C. In other embodiments thecomponents are heat resistant up to temperatures above 400° C.

In some embodiments, gas extraction duct 123 is omitted. A gas exhaustpassage may be formed or provided in top plate 114 providing a similarfunction to gas extraction duct 123. Pressure relief valve 128 may beplaced in the gas exhaust passage at or near end cap 108. End cap 108may be made of metal in some embodiments. In other embodiments, gasextraction duct 123 is formed as part of the rack carrying the batterymodules.

Where a component (e.g. cell, pouch cell, battery module, gasket, duct,pipe, valve, etc.) is referred to above, unless otherwise indicated,reference to that component (including a reference to a “means”) shouldbe interpreted as including as equivalents of that component anycomponent which performs the function of the described component (i.e.,that is functionally equivalent), including components which are notstructurally equivalent to the disclosed structure which perform thefunction in the illustrated exemplary embodiments.

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations thereof. For example:

-   -   The illustrated embodiment of battery module 100 is        representative of a battery module for which a thermal runaway        and gas exhaust management system 102 can be provided according        to embodiments of the invention. However, it is not necessary        that battery module 100 have all of the features as shown and        described. As will be appreciated by one of skill in the art,        other embodiments of the thermal runaway and gas exhaust        management system 102 described herein may work with other types        of battery modules having features that are different from the        ones that are described. For example, in other embodiments for        which thermal runaway and gas exhaust management system 102 is        provided, battery module 100 may be of the type that has stacked        battery cells that are held together by and housed within an        enclosure (as opposed to having interlocking cell carriers or        cell carriers that are secured together using straps as shown in        FIGS. 1-3). In some embodiments, battery module 100 may        incorporate other types of cells such as cylindrical 18650 or        27650 cells or prismatic cells, which may be housed in an        enclosure of any shape or size. Thermal runaway and gas exhaust        management system 102 including a gas extraction duct 123 and        self-closing, one-way pressure relief valve 128 may be        incorporated into such battery modules 100 to move hot gases        into a gas exhaust piping system 135 and away from the module.    -   More than one battery module 100 can be housed in a single        enclosure. In such embodiment, the enclosure may contain a        pressure relieve valve 128 for managing the movement of gases        from a gas extraction duct 123 extending through one or more of        the battery modules 100. The gas extraction duct 123 connects,        by way of the pressure relief valve 128 and a nozzle 130, to a        gas exhaust piping system 135 for carrying the hot gases to a        remote burn-off location.    -   It is not necessary that the pressure relieve valve 128 be        located at the rear of the battery module 100 as shown in the        illustrated embodiment. In other embodiments, pressure relief        valve 128 may be located at a side, top, and/or center of the        battery module 100, for example.    -   In some embodiments, more than one duct 123 may be provided in        each battery module 100 to collect the exhaust gases from        battery cells. For example, two or more ducts 123 may be aligned        parallel to one another and extend along a length of the cell        stack.        It is therefore intended that the scope of the following        appended claims and claims hereafter introduced should not be        limited by the embodiments set forth in the examples, but should        be given the broadest interpretation consistent with the        description as a whole.

What is claimed is:
 1. A method of manufacturing a battery module withan integrated thermal runaway management system, comprising: forming acell stack and positioning a top plate over the cell stack; forming aslot in the top plate, the slot extending between front and rear ends ofthe cell stack; placing a duct within the slot for collecting escapedgases from the cell stack; and placing a pressure relief valve in theduct toward the rear end of the cell stack.
 2. The method of claim 1comprising connecting the pressure relief valve to a piping system forcarrying gases collected in the duct to a remote location.
 3. The methodof claim 1 wherein the pressure relief valve is a self-closing, one-wayvalve.
 4. The method of claim 1 wherein the pressure relief valve has anoperating pressure of 7 kPa.
 5. The method of claim 1 comprising sealingthe top plate to the cell stack using a gasket.
 6. The method of claim 1wherein forming the cell stack comprises stacking cell carriers one ontop of the other, each carrier containing a battery cell.
 7. The methodof claim 6 comprising sealing each carrier to an adjacent carrier usingan inter-carrier gasket.
 8. The method of claim 1 comprising sealing theduct to the cell stack using a duct gasket.